There are several options for restoring speech to patients who have had their larynx removed. One procedure is to surgically create a puncture or fistula between the tracheal and the esophagus. A trachea voice prosthesis containing a one-way valve such as a BLOM-SINGER® voice prosthesis is inserted into the trachea-esophageal fistula. The one-way valve protects the airway during swallowing but opens under positive pressure. The voice prosthesis, thus, permits a patient to divert air from the lungs into the esophagus and out through the mouth. Speech is created during passage of air through the upper part of the esophagus.
The prosthesis maintains the fistula open, transfers air from the trachea to the esophagus for voice production and prevents esophageal leakage into the trachea during swallowing. However, the prosthesis being in contact with moisture in a hot, dark environment is subject to growth of commonly found yeast formation, typically Candida Albicans on the valve and the retaining flange. The growth of yeast can interfere with function of the valve and can cause the flange to wrinkle and leak.
The current low pressure voice prosthesis can be removed by the patient every few days and can be replaced with a clean prosthesis. The removed prosthesis is soaked in hydrogen peroxide to remove the layer of yeast from the valve and flange. Some patients such as quadriplegic patients or patients suffering from neurological conditions such as Multiple Sclerosis have difficulty managing frequent removal and reinsertion of the prosthesis. Others, who are physically handicapped are not able to remove, sterilize, or reinsert the prosthesis.
A longer dwelling, low pressure voice prosthesis has been developed that can remain in place in the trachea-esophageal fistula for over 3-4 days, depending on the patient and conditions of use. The patient can confidently use the prosthesis for longer periods. Trips to a health care specialist to remove and replace the prosthesis are greatly extended providing increased comfort and lower cost to the patient.
The flange or collar that rests against the trachea-esophageal wall is strengthened by increasing the thickness and/or diameter of the flange. The stronger flange is more resistant to wrinkling or detachment from the wall. The voice prosthesis can remain in place in the fistula for much longer periods without allowing leakage between the trachea and the esophagus. The stronger and larger collar also reduces possibility of dislodgement of the prosthesis during a coughing or sneezing episode. However, the thicker and wider flange is more difficult to insert through the fistula and does not reliably seat on the trachea-esophageal wall.
Yeast growth on the valve can also cause distortion of the shape of the valve or form wrinkles in the body of the valve which prevents the valve from closing.
Leaking also appears to be due to distortion of the valve body adjacent to the seat of the valve and to yeast growth on the seat. Forming the valve with an arcuate dome shape increased resistance to folding or bending of the valve. However, some valves still leaked after extended placement in a fistula.